Studies of human bone marrow treated with soybean lectin and sheep erythrocytes: stepwise analysis of cell morphology, phenotype and function.

Morphological, phenotypic and functional analyses were made of cells obtained at each step after successive treatments of 23 separate human bone marrow suspensions with soybean lectin and sheep erythrocytes (SRBC). The average total number of nucleated cells harvested was 1.9 X 10(10) and the final cell suspensions contained a mean of 1.9 X 10(9) nucleated cells or 9.2 +/- 4.8% of the initial counts. Monoclonal antibody analyses revealed that both T and B lymphocytes were present in every cell fraction in percentages similar to those found initially until after the first SRBC rosette-depletion. Moreover, both soy lectin agglutinated and non-agglutinated cells exhibited vigorous proliferative responses to phytohaemagglutinin and allogeneic cells. Following the SRBC depletions, no cells having T lymphocyte phenotypes or functions could be detected, whereas 5% of the cells reacted with a monoclonal antibody to B lymphocytes. The final fraction was composed predominantly of immature myeloid cells and blasts and was depleted of erythroid elements, lymphocytes and essentially all mature cells. It contained cells reactive with monoclonal antibodies recognizing undifferentiated T cell precursors (3A1), the transferrin receptor (5E9), and a human progenitor cell antigen (My-10). The final fraction was also enriched 10-100-fold for CFU-C and 5-10-fold for CFU-GEMN colonies. These studies fail to demonstrate selective removal of T lymphocytes from human bone marrow cells by soybean lectin agglutination.